1. Field of the Invention
The present invention relates in general to vehicle headlamps, and more particularly, to vehicle headlamps of a so-called "projector type" which comprises an ellipsoidal light reflector with first and second focuses, a light source located at the first focus, a shade member located in the vicinity of the second focus and a converging lens located in front of the shade member.
2. Description of the Prior Art
One type of conventional headlamps of the above-mentioned projector type is shown in Japanese Utility Model First Provisional Publication No. 54-109856.
In order to clarify the task of the present invention, the headlamp of that publication will be outlined with reference to FIGS. 22 and 23 of the accompanying drawings.
The headlamp comprises an ellipsoidal light reflector 2 which has an optical axis designated by numeral 1. A lamp bulb 4 is located at a first focus f.sub.1 of the reflector 2, and a shade member 7 is located near a second focus f.sub.2 of the reflector 2 having its upper edge contact with the optical axis 1. A coverging lens 6 is located in front of the second focus f.sub.2. As shown in FIG. 7, the upper edge of the shade member 7 is partially slanted.
When the bulb 4 is energized and thus produces light rays, the light rays directed toward the reflector 2 are reflected forward by the same and converged at the second focus f.sub.2 of the reflector 2. Due to presence of the upper edge of the shade member 7 near the second focus f.sub.2, part of the light rays from the reflector 2 is shaded. Thus, the light beam projected forward from the converging lens 6 has a contoured cross-sectional pattern with an inverted image of the upper edge of the shade member 7. Due to this, the beam produced by the headlamp is relatively small in sectional area as compared with that of a commonly used vehicle headlamp.
However, the above-mentioned projector type headlamp has the following drawbacks.
That is, the beam pattern produced by such headlamp is fixed relative to the vehicle on which the headlamp is mounted. This means that the influcence of the beam pattern (viz., blinding phenomenon) to the driver on an approaching vehicle on the opposite lane greatly changes depending on whether the vehicle is running on a straight road or a curved road.